The Endocrine Pancreas Flashcards
How do you calculate Body Energy?
Energy Intake - Energy Output
Where is energy intake determined?
The feeding centre (promotes hunger and drive to eat)
The satiety centre (promotes fullness by supressing feeding centre)
What is glucostatic theory?
Food intake is determined by blood glucose. As BG increases, the drive to eat decreases
What is the lipostatic theory?
Food intake is determined by fat stores. As fat stores increase, drive to eat decreases.
What is leptin?
A peptide hormone which is released by fat stores which depresses feeding activity
Name the three categories of energy output?
Cellular work, mechanical work and heat loss
Define Cellular Work
Transporting molecules across membranes, growth and repair, storage of energy
Define mechanical work
Movement on a large scale, using muscle, or intracellularly
Define heat loss
Associated with cellular and mechanical work. Accounts for half of our energy output
Define metabolism
The integration of all biochemical reactions in the body
What three elements make up metabolism?
Extracting energy from nutrients in food, storing that energy, utilising that energy for work
What are anabolic pathways?
Build up
Synthesis of large molecules from smaller ones, usually for storage purposes
What are catabolic pathways?
Break down
Degradation of large molecules into smaller ones, releasing energy for work
What is the absorptive state?
Where ingested nutrients supply the energy needs of the body and excess is stored.
When do we enter an absorptive state?
After eating
What is a fasted state?
Where we rely on body stores to provide energy between meals and overnight
What nutrient does the brain use?
Glucose
What can hypoglycaemia result in?
Coma and death
How is blood glucose maintained?
Via synthesising glucose from glycogen or amino acids
What happens to glucose in diabetes?
Glucose cannot be taken up so BG rises and glucose is detected in the urine
What is the normal range of blood glucose?
4.2-6.3 mM
Hypoglycemia = <3mM
Where are endocrine hormones produced?
The Islets of Langerhans
What are the four types of islet cells?
alpha, beta, delta and F Cells
What do alpha islet cells produce?
GLUCAGON
What do beta islet cells produce?
INSULIN
What do delta islet cells produce?
SOMATOSTATIN
What do F cells produce?
Pancreatic polypeptide
When does insulin dominate?
During the fed state
When does glucagon dominate?
During the fasted state
What is the function of insulin ?
To stimulate glucose uptake and lower blood glucose concentration
ALSO:
-stimulates glycogen synthesis, increases amino acid uptake into muscle, increases protein synthesis, increases TAG synthesis, inhibits gluconeogensis, promotes K+ion entry into cells, has permissive effect on GH
How is insulin synthesised?
As preproinsulin which is converted to proinsulin in ER
Give examples of insulin sensitive tissues?
Muscle and adipose tissue
How does insulin stimulate glucose uptake?
By stimulating GLUT-4 to migrate to cell membrane so glucose can be transported into cell. Insulin stimulation stops= GLUT 4 return to cytoplasmic pool
Where is insulin degraded?
The kidneys and liver
When is insulin released?
When BG conc is increased, when plasma amino acid conc. is increased, when glucagon has been stimulated
When is insulin inhibited?
Low blood glucose conc, somatostatin synthesis, stress
What is the function of glucagon?
To raise blood glucose
ALSO:
- increases glucogenolysis
- increases gluconeogenesis
- ketogenesis
Where does glucagon act?
UPON THE LIVER
Where is glucagon degraded?
The liver
What occurs when Glucagon is released?
Blood glucose concentration increases
When is glucagon released??
When [BG] is <5.6mM
What stimulates glucagon release?
Low [BG], High [amino acid]. sympathetic innervation, epinephrine, cortisol, stress
What inhibits glucagon release?
Glucose, FFA and Ketones, Insulin, Somatostatin
What happens to insulin and glucagon during parasympathetic activity?
Increase in insulin, small increase in glucagon
What happens to insulin and glucagon during sympathetic activation ?
Increase in glucose mobilisation, increase in glucagon, increase in epinephrine and inhibition of insulin
What is the action of somatostatin?
To inhibit GI tract activity by slowing nutrient absorption
Where is Somatostatin produced?
D cells of pancreas
What is the effect of exercise on [BG]?
Glucose entry into skeletal muscle increases
Insulin sensitivity increases
What is type 1 diabetes?
An autoimmune disease where pancreatic Beta Cells are destroyed, thus ability to produce insulin is decreased.
What occurs if type 1 diabetes is left untreated?
Starvation and death
What occurs in type 2 diabetes?
Peripheral tissues lose sensitivity to insulin = INSULIN RESISTANCE
How is type 2 diabetes treated?
Diet and exercise to try and restore insulin sensitivity
Metformin
Sulphonylureas
What are some complications of diabetes?
Retinopathy, neuropathy, nephropathy, CV Disease
